Magnetic recording device



Oct. 28,' 1947. H.A. vAGTBoRG ITAL 2,429,703

l MAGNETIC RECORDING DEVICE Raymond err/1er'v by n E;

Oct. 28, 1947. H. A. vAGTBoRG E1' Al. 2,429,703

MAGNETIC R'acomami` DEVICE Filed Dec. 26, 1942 2 Sheets-Sheet 2 PatentedOct. 28, 19247 MAGNETIC RECORDING DEVICE Harold A. Vagtborg and MarvinCami-as, Chicago,

and Raymond E. Zenner, Brookfield, Ill., assignors to Armour ResearchFoundatiomchicago, Ill., a corporation oi.' Illinois ApplicationDecember 26, 1942, Serial No. 470,208

- s claims. 1

This invention relates to improvements in a magnetic recording device,wherein a sound recording, such for example as the human voice, may bemade by magnetizing an elongated traveling recording medium in the formof a paramagnetic tape, paramagnetic wire, or the equivalent.

We are aware that in the past many and various types of magneticrecording devices have been developed,land in these devices a magneticrecording is made by successively magnetizing increments of thetraveling recording medium. However, insofar as we are aware, not any ofthese previously known devices have been both portable to an ultimatedegree and wholly selfenergizing, that is, having embodied thereineverything necessary for satisfactory and eilicient operation.

Under certain circumstances and conditions it is highly desirable tohave a magnetic recorder which requires no outside connections of anykind, and which is sumciently portable to be carried in a pocket orknapsack on the person so as to be available for instant usageregardless of the locality of the bearer. A device of such characterwould be extremely convenient for use by a military ofcer or otherperson on inspection duty whereby comments, orders, suggestions,information, etc. would be immediately dictated by such oflicer orperson for later reproduction and transcription. Such a device wouldalso be extremely convenient for recogniranceA duty, enabling therecognizance man to directly dictate reports at the instant he makesobservation, and for many other military and civilian duties, providinga record of events or observations which is substantially indestructableunless intentionally ruined, and which, if lost, is of little value tothe nder unless the nder has adequate apparatus to reproduce therecording.

With the foregoing in mind, it is an important object of the instantinvention to provide a selfsufcient magnetic recording device which isof such small size as to be carried within a pocket of the user, andwhich requires no outside connections or other apparatus in order tooperate conveniently and eflciently.

Another object of the invention is the provision of a compact magneticrecording device which embodies its own power supply and which willvperform eiliciently Without the aid of any connections to outsideapparatus.

It is also an object of this invention to provide a magnetic recordingdevice especially arranged to handle a scramble-wound recording medium,

2 eliminating the necessity of rewinding such scramble-wound mediumbefore it is used in connection with the present invention.

Also a feature of the invention resides in the provision of a magneticrecording device having guide means to provide for the very facileinsertion of the recording medium in position to have a record placedthereon by way of magnetlzation.

Another feature of the invention resides in the provision of a lightweight compact, highly portable magnetic recording device equipped withmeans not only for the purpose of magnetizing the traveling recordingmedium in accordance with sound being recorded, but also equipped with.means to condition such medium prior to a new recording being placedthereon, thus eliminating the necessity of a separate operation todemagnetize and rewind a recording medium before it is used again on theinstant recording device.

Still another object ofthe invention resides in the provision of ahighly portable, light weight magnetic recording device arranged for onehand support and operation during its use.

A further object of the invention resides in the provision of a. highlycompact readily portable magnetic recording device including its ownpermanently attached sound pick-up element, eliminating the necessity ofthe operator carrying any additional or spare parts for the device, withthe possible exception of an extra spool of recording medium in theevent a longer than usual recording is contemplated.

Still a, further object of the instant invention is the provision of ahighly portable and compact magnetic recording device which isselfsuiiicient, even to the extent of having its own speed control,means to prevent over-run of the supply spool of the recording medium,and provided With simple stop mechanism to control the operation of thedevice.

It is also an object of this invention to provide a highly portable,compact and self-suillcient magnetic recording device wherein arecording is made by successively magnetizing a traveling recordingmedium, the device being equipped with a spring motor forvoperating themechanism to move the recording medium.

While some of the more salient features, characteristics and advantagesof the instant invention have been above pointed out, others will becomeapparent from the following disclosures, taken in conjunction with theaccompanying drawings, in which:

Figure 1 is a vertical sectional view taken through the front part ofthe casing of a. magnetic recording device embodying principles of theinstant invention, illustrating salient parts of the device inelevation.

Figure 2 is a vertical sectional vview taken through the rear portion ofthe casing of the recording device seen in Figure 1, illustratingsalient parts of the device in elevation.

Figure 3 is plan sectional view of the device of Figures 1 and 2, takensubstantially as indicated by the section line III-III of Figure l,looking in the direction of the arrows;

Figure 4 is a transverse vertical sectional view taken substantially asindicated by the staggered line IV-IV of Figure 3, with certain partsshown in elevation for clarity;

Figure 5 is a fragmentary enlargement of the structure seen in the lowercentral portion of Figure 3, with the guiding means for the insertion ofthe recording medium removed; l

Figure 6 is a front elevational viewy of the structure seen in Figure 5;and

Figure 7 is a simplified schematic diagram showing a satisfactoryelectrical hook-up for the instant invention.

As shown on the drawings:

In Figures 1 to 6 of the drawings, the mechanical features of theillustrated embodiment of this invention are shown, the electricalconnections being omitted, as well as certain parts of apparatusembodied in the electrical hook-up such as a battery, transformer, etc.It will be understood that the electrical connections as well as suchapparatus as may be embodied exclusively in the electrical circuit aredisposed within the 35 casing containing the mechanical partsillustrated in Figures 1 to 6 inclusive in any suitable location notoccupied by other apparatus. 'I'he salient elements of the electricalcircuit are indicated in simplified schematic form in Figure 'Z 40 4mounted on a suitable stub shaft, which engages the partition 3, forfree rotation.

, Near the opposite end of the panel 3 is a similar reel or spool I2which functions as a pickup or receiving reel upon which the recordingmedium is wound after it has been magnetized in accordance with theparticular sounds to be recorded. During its travel from the spool I0 tothe spool I2, the recording medium II -`may be both cleaned andmagnetized again in accordance with a newly desired sound record. Afterthe recording medium has been wound on the spool I2, it is a simpleexpedient to remove this spool, place the spool I0 in the position of-spool I2, and insert a new supply spool in the position formerlyoccupied by spool l0.

The spool I2 is a driven spool and is mounted on the end of a drivenshaft I3 extending through the partition 3. This shaft carries a gear I4 in the rear compartment 'of the casing which is enmeshed with aconsiderably larger gear I5 fixed to a rotatable spring housing I6floating on a shaft I'I. As best seen in Figure 2, a flat spring I8 iscoiled within the housing I6, one end of the spring being anchored tothe housing I3 as indicated at I9, and the other end of the spring beinganchored to the shaft I1 as indicated at 20.

'I'he shaft I1 extends rearwardly to a vertically so disposed support 2lcarried by the partition 3 the size of the bottom, and an inner channel60 shaped partition 3 xedly attached to both the top and the bottom. Endwalls l, and 5 of substantially the same width as the top 2 may beintegral or attached to the bottom I and top 2 to form a box-likeconstruction closed on one side by the partition 3 and on the other sideby a back cover 6 pivoted to the bottom as indicated at 1. On theopposite side of the partition 3, the complete closure is made by abox-like front cover 3 pivoted as indicated at 9 on the bottom member I.It is therefore apparent that when the cover 3 and back panel 6 areswung downwardly, all of the apparatus contained within the casing onboth sides of the partition 3 is readily available for attention. Anysuitable form of latching or locking means may be used to hold the backand front covers of the casing in closed position.

Mounted on the partition 3 near one end thereof and inside the frontcompartment of the casing is a reel or spool lli which functions as asupply spool, carrying a supply of recording medium which in theillustrated instance is in the form of a fine round wire Il.

o at 3|.

with the aid of a plurality of bolt and spacer sleeve connections 22, asseen clearly in Figure 3. On the rear side of the support 2i the shaftI1 has a ratchet wheel 23 keyed thereto. This ratchet wheel is engagedby a bell crank pawl 2l pivoted as indicated at to the support 2|, andmaintained in engagement with the ratchet wheel by a tension spring 26,as clearly seen in Figure 2. Thus, the shaft Il is prevented fromturning by action of the spring I8, and when the spring is wound, theopposite end of the spring namely, the point of attachment` I9 with thespring housing, is the only one free to move, and so the spring housing,together with the gear I5, is rotated as the spring tends to unwind.With reference again to Figure 2, it will be seen that the exposed endof the shaft l1 is provided with a diametral rib 21 and, as seen best inFigure 3, a key 28 having a complemental end configuration may beinserted through an aperture in the back panel 3 into engagement withthe shaft II for winding up the spring.

Of course, rotation of the spring housing I6 together with the gear I5causes rotation in the opposite direction of the gear I4 and likewisethe shaft I 3 carrying the take-up spool I2. To maintain substantiallyconstant speed of the spool I2 during operation, the rearwardlyextending end of the shaft is provided with a suitable governingarrangement generally indicated by numeral 29 in Figure 3 which may bein the form of a friction brake or any equivalent structure, details ofwhich are not necessary to illlustrate herein.

The start and stop control for the magnetic recording device is bestseen in Figures 2 and 3. With reference to these figures it will benoted that a lever 30 projects through a suitable opening in the endwall E of the casing, and this lever is pivoted to the aforesaidpartition 3 as indicated The inner end of the lever is shaped forengagement between adjacent teeth of the gear I4 as indicated at 32 inFigure 2, so that when such engagement is established, the levereffectively prevents rotation of the gear Il and like- This reel I0 is75 wise the gear I5 and spring housing I3. In order `which the leverextends. A simple flick of the finger or thumb will then release thelever from the notch, and the spring 33 will return the inner end 32 ofthe lever into engagement with the gear I4 and not only stop but holdthe device in stop position. If desired, a suitable switch forenergizing the electrical circuit embodied in the invention may beincorporated with this lever, so that the switch will be closed when theleveris moved to running position, and the switch will automatically -beopened when the lever is moved tostop position,

In view of the fact that a sudden stopping of operation may permit aslight over-run or coasting of the supply spool III so as to providesome slack in the wire immediately following the cessation of operation,a leaf spring 35 is mounted on the inner partition 3 in a manner toconstantly bear against the inner side surface of the spool I 3, as seenclearly in Figure 3, to thereby provide suiiicient braking action toprevent over-run or coasting of the spool I0, but not suilicient brakingaction to interfere with normal operation of the device.

Now with reference to Figures 5 and 6, it will be seen that the wire IIin traveling from the reel III to the reel I2 ilrst passes between ahorizontally disposed pulley 36 and a horizontally disposed pulley 31,then through the upper portion of a magnetic recording head 38, and overa vertically disposed pulley 33 to the reel I2. The pulleys 36 and 31are staggered with respect to the desired path of travel of the wire II.but it will be noted with reference to Figure 5 that the bottoms of thegrooves in these two pulleys are in alignment with a groove 40 in themagnetic recording head 38 through which groove the wire must pass. Thisgroove 40 is also in direct alignment with the upper point in the bottomof the groove of the vertically disposed pulley 39. Consequently, if thespool I0 contains a supply of scramble-wound wire, that is, wire thatwas wound haphazardly upon the spool with little or no level windingattempt, the pulleys 36 and 31 will line up such scramble-wound wire sothat it will pass directly through the groove in the recording head,over the pulley 33, and evenly onto the reel I2.

To insure a level wind of the wire II on the reel I2, a mechanism isprovided which includes a plate 4I pivoted at 42 to the horizontal faceof an L-shape bracket 43 attached to the inner partition 3 of thecasing. The plate 4I supports the pulleys 36 and 31, the magnetizing orrecording head 38, and the pulley 33, so that all of these pulleys andthe recording head must move backwardly and forwardly with the swing ofthe plate 4I. With reference more particularly to Figures 3 and 5, itwill be seen that a cam riding projection 44 extends laterally from theplate 4I through an opening 45 in the partition 3 into contact with thesurface of a cam 48 carried by the aforesaid spring housing I6 and gearI5. The cam 46 is provided with such a surface vthat the plate 4I willbe pivoted around the point 42 backwardly and forwardly during turningof the gear I5.

Thus, due to the pivotal movement of the plate 4 I, together with thevarious pulleys and recording head carried by this plate, the wire isaccurately level wound upon the spool or reel I2. On the opposite sideof the plate 4I from the cam rider 44, this plate is provided withanother projection or lug 41, and a similar lug 48 extends from theiixed'bracket 43. Between these lugs, a tension spring 43 is disposed soas to hold the plate 4I in operative connection with the cam 46. All ofthe pulleys 36, 31 and 33 are idler pulleys and rotate by the frictionof the wire thereagalnst.

Means are also provided to insure or facilitate a ready and easythreading of the recording medium into its proper position when a newsupply roll I0 is placed upon the device. It would be an extremelydifllcult operation to thread the end of a wire between the pulleys 36and-31, into the groove 40 of the `recording head, and over the pulley33, and then maintain that wire in proper position while the end of thewire was anchored to the receiving spool `I2. To obviate any suchdifficulty, yet accomplish the same purpose in a very facile manner, thewire is first taken from the spool AIIl and attached directly to thespool I2. 'I'hen the spool I0 is rotated slightly to provide some slackin the wire between the two spools. This slack portion of the wire isthen pushed through an open bottomed groove 50 in a guiding member 5Iwhich is secured to the mov- `able plate 4I by bolts 52 or in any otherlequivalent manner. As seen best in Figure 4, the guide 5I is in theshape of an inverted channel, and the groove 53 is formed in the natureof a superstructure extending upwardly from the bottom of the channel.In that portion of the guide member that passes directly over therecording head 38, it will be seen that the groove 5I! of the guidemember is spaced directly over and parallels the groove 40 in therecording head. With reference to Figure 3, it will also be seen thatthe groove 50 in the guide member curves in keeping with the staggeredpulleys 36 and 31 .as indicated at 53, so that the groove of the guidemember is disposed in such a manner that a wire pushed therethrough willpass by the flange on each of these pulleys.

When the wire II is threaded through the groove in the guide member 5I,past the flanges on the pulleys 36 and 31, into the groove 40 of therecording head 38, and into the groove of the vertically disposed pulley33, the reel I0 is then preferably turned backward suiliciently to takeup the slack in the wire, and the wire will then seat within the groovesof the pulleys 36 and 31, properly seat within the groove 40 in therecording head, and ride the groove of the pulley 33. It is an extremelysimple expedient to push the slack portion of the wire through thegroove 50 in the guide member 5I and an expedient that may beaccomplished with a minimum of time and effort.

In order to make this device quite self-sufficient, amicrophonestructure is preferably built on the back wall of the device asindicated at 54, so that all that is necessary for the operator to do isto talk directly into the part 54 when making a recording on the wire II.

In Figure '1 we have illustrated a simplified form of wiring diagramshowing an electrical circuit satisfactory for use with the instantinvention. In this diagram, the aforesaid microphone or other pick-updevice 54 is connected at one side to a battery 55 and to a ground 56.The other side of the microphone is connected through a conductor l1 tothe primary coil of a transformer 7 58. The other side of the battery isconnected by way of conductor '9 to both the primary and secondary coilsof the transformer 58. The opposite end of the secondary coil isconnected through conductor 80 to a magnetizing coil 6I in the recordinghead 38, and the other end of the magnetizlng coil is grounded asindicated at 82. The recording head 38 in general comprises a core whichis preferably laminated, and the coil 6I is disposed around one leg ofthis core. The upper leg of the core is provided with the groove 48through which the recording medium travels, and this leg is dividedtransversely by a relatively narrow air gap so as .to provideconfronting pole faces of opposite polarity. It is over the region ofthis air gap that the recording medium receives its successivemagnetizations during the making of a recording on the wire.

may be supplied by a single battery, and this battery as well as thetransformer and the necessary wiring may all be contained Within thecasing in locations not occupied by other apparatus, the

partition 3 being apertured to provide passage,

way for the wiring wherever necessary. Preferably, the battery may belocated in the space beneath the bracket 43 in the front compartment ofthe casing where it is readily accessible for removal and replacing. Itwill be apparent from the description and showing of the circuit thatsound introduced through the microphone 54 will cause a variation inintensityof the current passing through the magnetizing coil 6|, andthus the recording medium Il will be variably magnetized in keeping withthe variations of the sound being recorded. In order to render thedevice capable of cleaning a wire having a previous recording thereon, apermanent magnet 63 may be disposed adjacent the path of the wire H infront of the recording head 38. It is not necessary that the end of thepermanent magnet actually contact the wire, but only that the magnet bein close proximity to the traveling wire. The action of such magnet uponthe wire is suiiicient to magnetically saturate the wire and thus wipeout any previous recording on the Wire so that the wire will be clean orwithout a recording when it reaches the recording head 38. In someinstances, especially with simpliiied circuits, it is desirable toemploy the magnet B3 to condition a totally demagnetized wire forrecording purposes by magnetically saturating the wire. This permanentmagnet 63 may be disposed in any suitable location along the path ofthe` wire in advance of the recording head 38, such for example as beingmounted upon the swingable plate 4I in position adjacent the wire as thewire passes the pulley 3l.

In operation, the present invention is extremely simple. Assuming thatthe spring I8 has been wound by the key 28, it is only necessary for theoperator to hold the device easily in one hand, and with a nger or .thethumb flick the starting lever 30 into running position and speak intothe microphone 54. At the end of the speaking, it is a simple expedientto ick the lever into stop position, and replace the entire device in apocket, knapsack, or the like. .The only operation on the part of theoperator necessary is periodically winding the spring, starting andstopping the device by the manipulation of the lever 30, and possiblyreplacing a supply spool of recording medium and now and then a battery,if such work is not done for the operator at his base. It will beappreciated that the recording may be continuous because the spring maybe wound during operation.

From the foregoing, it is apparent that we have provided a highlycompact and self-sunlcient recording device, which is not only pocketsize, carries its own power, is enabled to handle scramble-wound wire,but is also capable of reconditioning a wire or other recording mediumprior to its new magnetization in accordance with the new recording. Itwill also be apparent that the device is designed for one handoperation, is equipped with a speed control, an over-run preventingmechanism, adequate starting and stopping means, and the microphone maybe built into a part of the casing. Consequently, there is no necessityfor the operator to connect the device with any outside source o! power,and it will be at once noted that the device is economical inconstruction and use.

It will, of course, be understood that various details of constructionmay be varied through a wide range without departing from the principlesof this invention and it is, therefore, not the purpose to limit thepatent granted hereon otherwise than necessitated by the scope of theappended claims.

We claim as our invention:

1. A portable magnetic recording device, including a pair of spools fromone to the other of which a recording medium is wound, means formagnetizing the traveling medium, a spring motor to drive the receivingspool, a casing containing all said structure, and sound pick-up meansin said casing in circuit connection with said magnetizing means.

2. In a magnetic recording device, a pair of spools from one to theother of which a recording medium is wound, driving means to actuate thereceiving spool, a pivotal member adjacent the path of the mediumbetween said spools, straightening means for scramble-wound mediumcarried by said member, magnetizing means carried by said member, cammeans associated with said driving means to swing said member back andforth to level-wind the medium on the receiving spool, and guide meansalso carried by said member to facilitate threading of recording mediuminto said straightening means and said recording means, said guide meansbeing in the form of a cover member having a bottomless groove shaped inkeeping with the path of the medium.

3. In a magnetic recording device, a pair of spools from one to theother of which a recording medium travels a'predetermined path, andstraightening means between said spools to direct scramble-wound mediumon the supply spool along said predetermined path to the receivingspool, said straightening means being in the form of staggered pulleys.

4. A self-contained and portable magnetic recording device, including apair of reels from one to the other of which a recording medium iswound, magnetizing means to act on said medium, spring drive means forone of said reels, an impulse pick-up element in circuit connection withsaid magnetizing means, a source of electrical energy for the circuitincluding the pick-up element and magnetizing means, and a pocketsizecasing containing all the aforesaid structure.

5. A self-contained and portable magnetic recording device, including acasing, a pair of reels in said casing, a recording medium on saidreels,

spools from one to the other of which a recording l0 medium is wound,driving means to actuate the receiving spool, a pivotal member adjacentthe path of the medium between the spools, staggered pulleys mounted onsaid pivotal member to straighten scramble-wound medium, magnetizingmeans carried by said member, and means as-` sociated with said drivingmeans to swing said member back and forth to level-wind the medium onthe supply spool.

HAROLD A. VAGTBORG. MARVIN CAMCRAS. RAYMOND lE, ZENNER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name 4 Date 898,283 Stuart Sept. 8, 19081,123,147 Sherman Dec. 29, 1914 1,191,182 Heymen July 18, 1916 1,886,856Warwick Nov. 8, 1932 2,078,357 Woodmansee Apr. 27, 1937

